Take another look at the sentence:
On his way to an interview, Gonzalo __________ a hot dog to quiet his rumbling stomach. While he was wolfing down this quick meal, yellow mustard dripped all over the front of his crisp white shirt.
The sentence requires the past tense of buy, an irregular verb. Bought is the simple past form.
|Verb||Simple Present||Simple Past||Past Participle|
Baught, the form you chose, is a spelling error. Before you continue, review the rules for irregular verbs.